To examine by light microscopy and by transmission and scanning electron microscopy the early interaction of cells that are presented with antigen. And specifically: To continue with scanning electron microscopy to: Characterize surface morphology of lymphocytes macrophages derived from the peritoneal cavity. Compare normal and immune cells in presence and absence of antigen. To describe surface morphology of cells that have differentiated into plasma cells in diffusion chambers. To prepare hybrid antibody to tag T and B cells for identification in SEM and to follow fate of these cells in differentiation in diffusion chambers and in the milk spots of the omentum. To continue with replica technique and to look at retention of HRP on macrophage surfaces.